Thanks for reporting this bug. Indeed, it looks as though the postrm script does 'rmdir --ignore-fail-on-non-empty' but that still raises an error when the directory does not exist, so should be '|| true'.
Thanks for reporting this bug. Indeed, it looks as though the postrm script does 'rmdir --ignore- fail-on- non-empty' but that still raises an error when the directory does not exist, so should be '|| true'.